Manacles, shackles, and handcuffs are portable locking devices used, e.g., by law enforcement personnel, to temporarily but securely bind or restrain suspects and other persons in custody. The basic modern handcuff design has proven very successful both in terms of functionality and low manufacturing costs, and has changed little over the years.
One typical design for double locking handcuffs is shown in U.S. Pat. No. 4,287,731. In the '731 patent, in a central cavity in the handcuff frame, a laterally-moveable spring element biases a pivoting bolt in a downwards direction against the cuff's pivoting jaw. The jaw and bolt have cooperating, oppositely facing ratchet teeth. When “single locked,” the jaw can be moved to tighten the cuff, but the bolt prevents the jaw from disengaging in a release direction. The cuff is unlocked entirely simply by using the handcuff key to rotate the bolt out of engagement with the jaw. For double locking the cuff, one end of the key has a small, pin-like protuberance. This is inserted into a small slot in the front of the cuff frame, and is moved from left to right to laterally shift the spring element. Once shifted, the spring element blocks the bolt, preventing it from being moved away from the jaw, while at the same time biasing the bolt against the jaw. In this manner, the jaw cannot move, and the cuff is rendered more difficult to pick or otherwise bypass. (It should be noted that once the spring element is laterally shifted, it lies past the slot and can no longer be engaged by the pin-end of the key.) To unlock the cuff, the key (placed in the keyhole slot) is rotated away from the bolt, contacting and laterally shifting the spring element. Then, the key is rotated the other direction to pivot the bolt away from the jaw.
Other double locking cuff mechanisms replace the slot with a small bore or hole that extends through the side of the frame and into the region of the end of the spring element. To double lock the cuffs, the pin-like end of the key is pushed into the hole to either directly push on the end of the spring element, or to push on an intermediate element (an internal pin) that in turn acts on the spring element.
While these and similar designs have proven to be effective in terms of general operation and robustness, the difficulties faced by law enforcement personnel have revealed the need for improvements in the area of situational functionality. In particular, restraining and handcuffing a suspect is one of the most dangerous and difficult operations faced by law enforcement personnel. Typically, the suspect is less than fully cooperative, and may in fact be making concerted efforts to resist arrest. This will require that the suspect be physically subdued, and even then there may be arm and leg movement.
In such situations, it is difficult in the first place just to position the cuffs for engagement around the suspect's wrists. Moreover, considering the very small size of the key and key pin-end, double locking the cuffs will be even more difficult. First, if not readily available, the handcuff key has to be located, a difficult task with an unruly suspect. Then, two hands may have to be used to hold the key, find the small front or side slot/hole in the cuffs, and maneuver the pin-end into the slot or hole. Such problems are compounded at night or in other low-light situations. Also, considering the potentially fast-moving situation, and in light of the small size of the double lock actuation components (e.g., key and hole or slot), it may not be possible for the officer to tell whether or not the double lock has actually engaged.
Accordingly, a primary object of the present invention is to provide an improved double lock mechanism for handcuffs that can be easily and quickly engaged by a law enforcement officer by hand and without the need for the handcuff key, and that provides a measure of positive feedback to the user indicating that the double lock mechanism has been actuated.